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Seminar 830  

Seminar:  830

1

Speaker(s)

Shu-Chun Chiu

Topic

Study on the Pathogenesis for Porcine Teschovirus and Production of the Classical Swine Fever Live Vaccines

Abstract

In Taiwan, PTV-1s were isolated and identified from clinical cases submitted to Animal Health Research Institute in years 2000, 2003, 2004, 2005 and 2006, respectively.  Based on these results, it is suggested that teschovirus infection may have occurred widely in pig population of Taiwan. In this study, experiments were done to realize the pathogenesis of porcine teschovirus. And then, we want to understand the RT in situ PCR methodology and the potential causes of background, it is important to be aware of the various pathways of DNA synthesis that may be operative inside an intact cell

Hog cholera (HC) or classic swine fever (CSF) is a highly contagious and fatal septic disease caused by a virus belongs to Pestivrus of Flaviviridea family. Severe outbreak had been reported in Taiwan during the period when it was occupied by Japanese. The situation has been put under controlled quickly when the LPC-China strain live vaccine has been developed successfully and been used island-widely in 1950s. The pig industry of Taiwan has therefore been protected and grew up prosperously. In response to the movement of piglets in early age, the government established a vaccination program for piglets depending on the vaccination program of sows.

2

Speaker(s)

Tzu-Ming Huang

Topic

Development of Inactivated Streptococcus iniae Vaccine

Abstract

Streptococcosis is a common disease in fish and responsible for significant economic losses in aquaculture. Streptococcus iniae, S. agalactiae, and Lactococcus garvieae are commonly isolated from fish streptococcosis. The prevention and control for fish streptococcosis includes antimicrobial chemotherapy and vaccine administration. The objective of the present study was to develop and improve inactivated vaccines against S. iniae for fish. Overnight culture of seed S. iniae strain with brain heart infusion broth achieving to exponential phase was inactivated by adding formalin with concentration to 0.5%. Safety and efficacy were evaluated in sea bass and king groupers. After intraperitoneal injection, there was no adverse reaction. The relative percent survival (RPS) was higher than 80% after challenge of seed strain in both species. Results of efficacy test showed good immune protection of the inactivated vaccine. Furthermore, immersion with 1x or 10x diluted-injection type vaccine in one minute or longer caused adverse reactions in sea bass. Lower concentration of formalin in inactivated vaccine could decrease the adverse reactions and increase the immersion duration. The safety and efficacy tests of immersion vaccine are undergoing. It was noted that the colony morphology, hemolysis, and biochemical characters were different between seed strain and strains isolated from Kaohsiung, Tainan, and Chiayi. Difference and crossover immune protection among different isolates of S. iniae should be considered for further vaccine development and improvement.

3

Speaker(s)

Shao-Hui, Cheng

Topic

Validation of a real-time TaqMan-based RT-PCR assay for the detection of nervous necrosis virus

Abstract

Viral nervous necrosis (VNN) is considered to be a serious disease of several marine fish species, characterized by significant economical losses associated to vacuolating lesions of the central nervous system and the retina. The causative agent of VNN is nervous necrosis virus, consists of two molecules of positive-sense ssRNA, which is identified as a member of the family Nodaviridae. This virus is an important quarantine requirement for the importation of live fishes in many counties. Because the special quarantine requirement of Vietnam, we set up a real-time TaqMan-based RT-PCR (reverse-transcriptase polymerase chain reaction) assay for detecting nervous necrosis virus in live fishes for export in our laboratory. In this report, we described results of the sensitivity, specificity and reproducibility of this method tested in our laboratory. From March to September this year, 126 samples from marine fish were tested by two methods, including the real-time TaqMan-based RT-PCR and the conventional RT-PCR. The positive rates of the samples tested by the real-time TaqMan-based RT-PCR and the conventional RT-PCR were 12.7% and 4.8%, respectively. The real-time TaqMan-based RT-PCR method is more sensitive than conventional RT-PCR. Using this method can assist the exportation of live fishes to Vietnam.